Limonin analogues are highly oxidized tetracyclic triterpenoids mainly existing in rutaceae and meliaceae plants. People have successively separated different limonin analogues since Bemay (1841) separated limonin for the first time, and have separated more than 300 limonin analogues from citrus plants and hybrid plants thereof at present.
In recent decades, people have found that limonin analogues in citrus fruits have many biological functions: antimalarial, antibacterial, anti-inflammatory, analgesic, insecticidal functions, etc., can effectively prevent pathogenic bacteria from encroaching on animal bodies, can expel parasites from animal bodies; can stimulate the activity of glutathione transferase, a main detoxification enzyme in vivo, and have very strong antitumor activity. Pesticide prepared from limonin analogues at a certain concentration is a natural, non-toxic and desired biopesticide with good insecticidal efficacy. Embedded limonin analogues can be very widely used as functional food additives. Japan has had a patent for producing functional food using limonin analogues. Limonin analogues also have activities, such as antioxidation, antitumor, exciting central nervous system, etc., have significant importance for the industries, such as human medicine, food, agricultural production, etc., and are bioactive substances with very high development value.
Limonin is an electrically neutral triterpenoid dilactone compound with a molecular formula of C26H30O8 and with a hydrophobic structure, is easily soluble in ester-soluble organic solvent, and is hardly soluble in water. The traditional limonin extraction method degreases and extracts dried raw materials with an organic solvent. The frequently used extraction method generally extracts limonin using the solubility of limonin in the extract and mainly using the solvent of dichloromethane, hexane, methanol, acetone, isopropanol, etc. At present, the widely used degreasing solvents include petroleum ether, ethyl ether, ethanol and methanol. The traditional method is expensive and time-consuming, and does not facilitate realizing industrialized production of limonin preparation.
Besides, a part of limonin is soluble in water solution in the form of limonin A-ring lactone, and is therefore difficult to be separated. Some researchers adsorb limonin in resin from an aqueous solution, and then elute adsorbed limonin with an organic solvent, which also needs to use a lot of organic solvent, needs recovery of the organic solvent, and has high process cost. For this reason, the inventor has researched and designed a limonin extraction method, thereby resulting in the present application.